Check the appropriate box to
designate the rule pursuant to which this Schedule is filed:

[X] Rule
13d-1(b)

[ ] Rule
13d-1(c)

[ ] Rule
13d-1(d)

*The remainder of this
cover page shall be filled out for a reporting persons initial filing on this
form with respect to the subject class of securities, and for any subsequent
amendment containing information which would alter the disclosures provided in
a prior cover page.

The information required
on the remainder of this cover page shall not be deemed to be filed for the
purpose of Section 18 of the Securities Exchange Act of 1934 (Act) or
otherwise subject to the liabilities of that section of the Act but shall be
subject to all other provisions of the Act (however, see the Notes).

The securities reported on herein are beneficially owned by one or more
open-end investment companies or other managed accounts which are advised or
sub-advised by Ivy Investment Management Company (IICO), an investment
advisory subsidiary of Waddell & Reed Financial, Inc. (WDR) or Waddell
& Reed Investment Management Company (WRIMCO), an investment advisory
subsidiary of Waddell & Reed, Inc. (WRI).
WRI is a broker-dealer and underwriting subsidiary of Waddell & Reed
Financial Services, Inc., a parent holding company (WRFSI). In turn, WRFSI is a subsidiary of WDR, a
publicly traded company. The investment
advisory contracts grant IICO and WRIMCO all investment and/or voting power over
securities owned by such advisory clients.
The investment sub-advisory contracts grant IICO and WRIMCO investment
power over securities owned by such sub-advisory clients and, in most cases,
voting power. Any investment restriction
of a sub-advisory contract does not restrict investment discretion or power in
a material manner. Therefore, IICO
and/or WRIMCO may be deemed the beneficial owner of the securities covered by
this statement under Rule 13d-3 of the Securities Exchange Act of 1934 (the 1934
Act).

IICO, WRIMCO, WRI, WRFSI and WDR are of the view that they are not
acting as a group for purposes of Section 13(d) under the 1934 Act. Indirect beneficial ownership is attributed
to the respective parent companies solely because of the parent companies
control relationship to WRIMCO.

(a)Amount
beneficially owned: 4,268,500

(b)Percent
of class: 10.9%

(c)Number
of shares as to which the person has:

(i)

Sole voting power to
vote or to direct the vote:

WDR: 4,268,500(indirect)

WRFSI: 3,689,900 (indirect)

WRI: 3,689,900 (indirect)

WRIMCO: 3,689,900 (direct)

IICO: 578,600 (direct)

(ii)

Shared power to vote or
to direct the vote: 0

(iii)

Sole power to dispose
or to direct the disposition of:

WDR: 4,268,500(indirect)

WRFSI: 3,689,900 (indirect)

WRI: 3,689,900 (indirect)

WRIMCO: 3,689,900 (direct)

IICO: 578,600 (direct)

(iv)Shared
power to dispose or to direct the disposition of: 0

Item 5:

Ownership of Five
Percent or Less of a Class:

If this statement is being
filed to report the fact that as of the date hereof the reporting person has
ceased to be the beneficial owner of more than 5 percent of the class of
securities, check the following: [ ]

Item 6:

Ownership of More than
Five Percent on Behalf of Another Person:

The clients of IICO and
WRIMCO, including investment companies registered under the Investment
Company Act of 1940 and other managed accounts, have the right to receive
dividends from as well as the proceeds from the sale of such securities. Waddell & Reed Advisors Funds, Inc.
Science and Technology Fund, a company registered under the Investment
Company Act of 1940, has an interest in more than 5% of the class of
securities reported herein.

Item 7:

Identification and
Classification of the Subsidiary Which Acquired the SecurityBeing Reported on By the Parent Holding Company:

See Attached Exhibit 2.

Item 8:

Identification and
Classification of Members of the Group:

Not Applicable.

Item 9:

Notice of Dissolution
of Group:

Not Applicable.

Item 10:

Certification:

By signing below I certify
that, to the best of my knowledge and belief, the securities referred to
above were acquired and are held in the ordinary course of business and were
not acquired and are not held for the purpose of or with the effect of
changing or influencing the control of the issuer of the securities and were
not acquired and are not held in connection with or as a participant in any
transaction having that purpose or effect.

SIGNATURE

After reasonable inquiry and to
the best of my knowledge and belief, I certify that the information set forth
in this statement is true, complete and correct.

Dated:February 1, 2006

Waddell & Reed
Financial, Inc.

Waddell & Reed
Financial Services, Inc.

By:

/s/ Wendy J. Hills

By:

/s/ Wendy J. Hills

Name: Wendy J. Hills

Name: Wendy J. Hills

Title: Vice President

Title: Attorney-In-Fact

Waddell & Reed,
Inc.

Waddell & Reed
Investment Management Company

By:

/s/ Wendy J. Hills

By:

/s/ Wendy J. Hills

Name: Wendy J. Hills

Name: Wendy J. Hills

Title: Attorney-In-Fact

Title: Attorney-In-Fact

Ivy Investment
Management Company

By:

/s/ Wendy J. Hills

Name: Wendy J. Hills

Title: Attorney-In-Fact

EXHIBIT INDEX

Exhibit
No.

Description

1

Joint Filing Agreement

2

Identification and
Classification of the Subsidiary Which Acquired the Security Being Reported
on by the Parent Holding Company